Overload protection device



April 1954 H. s. METZGER 3,130,613

OVERLOAD PROTECTION DEVICE Filed Feb. 13, 1961 United States Patent3,130,613 OVERLOAD PROTECTION DEVICE Hans Siegfried Metzger, 33 Auf derTeufelsinsel, Saint-lnghert (Saar), Germany Filed Feb. 13, 1961, Ser.No. 88,991 Claims priority, application Germany Feb. 12, 1960 7 Claims.(Cl. 80-57) The present invention relates broadly to an overloadprotection device having an interchangeable breaker block locatedbetween parts of machines which are loaded by opposing pressure-forces.

More particularly, this invention relates to a breaker blockconstruction located between the screw-downs and the checks in rollingmills. By the provision of such breaker blocks the rolls, the bearings,and last but not least the housing of a rolling mill are to be protectedagainst damages which can result from excessive rolling pressure.

The problem is that the effective breaking load of breaker blocks knownin the art cannot be accurately computed or calculated. Therefore,breaker blocks having the same dimensions might break at different highrolling pressures, so that unnecessary shut-down time, or damage to themachine parts might occur, and which eventualities should be avoided.

These difiiculties arise from the fact that in the conventional types ofbreaker blocks, different kinds of stresses occur, namely predominantlybending and shearing stresses. Moreover, such breaker blocks'in manycases entail an undesirable resiliency. In metal rolling mills suchresiliency means less accurate tolerances of the stock.

It is therefore an object of this invention to provide an overloadprotection device, featuring a breaker block the breaking load of whichcan be accurately computed or calculated.

It is a further object of the invention to provide an overloadprotection device, featuring a breaker block in which only or mainlytension stresses occur.

A still further object of the invention is to provide an overloadprotection device of the aforementioned type which has the lowestpossible inherent resiliency.

These objects are obtained by this invention by introducing the opposingpressure forces of the system into the breaker block in such anoverlapping manner that in the breaking point cross-section of thebreaker block, tension stresses are created. The machine parts in whichpressure forces are evident, therefore, attack the breaker block in anoverlapping manner, so that in the cross-section between the areas ofattack of the forces, a breaking point cross-section is subjected totension stresses only. These tension stresses can be accurately computedin advance, and thus the eflective breaking load can also be accuratelycomputed. The material providing the breaking point cross-section can beprovided with a very short length of elongation, whereby the breakerblock is imparted with a high elastic recovery force.

There are various possibilities of putting into practice the principleof the invention. In particular, for application to rolling mills, it isfurther proposed that the breaker block should have the shape of a pot.The opposing pressure forces are introduced both into the rim and intothe pot-bottom which should have as much resistance to bending aspossible. The breaking point cross-section is provided for in the wallof the pot. This particular shape not only saves space but has theadvantage, due to the circular or annular shape of the breakingcross-section, of facilitating the subjecting of the steel-pot to a mosteffective heat treatment. The breaking cross-section, which isdistributed over a relatively wide circumference, can be highly temperedand therefore, receive a uniform grain.

Further objects and advantages of the invention will be apparent fromthe following description taken in conjunction with the accompanyingdrawing which is a fragmentary View illustrating an embodiment of theinvention partially in vertical section and partially in elevation.

In the drawing the machine parts with which the breaker block isassociated are illustrated as constituting an adjusting screw 1supported by a cross frame or transverse 2 of a rolling mill housing andan upper chock 3 of a mill stand. As is known in the art, chock 3 willhave to rise in order to relieve any force on the rolls, not shown. Therolling pressure is directed upwardly from the chock via an axiallydivided or split supporting ring 4 into the outwardly directed flange orrim 5a of a breaker block 5 of pot-shape form. The counter or what couldbe downwardly directed pressure force is exerted on the bottom 5b of thepot 5 via an intermediate piece or block 6. Thus the upwardly directedforce passes from ring 4 through the pot 5 and block 6 into the end face1a of the adjusting screw 1. The end face In is shaped as a sphericalsocket, whereas the upper pressure transmitting surface 6a of theintermediate block 6 is likewise of spherical shape. This shaping ofthese two contacting faces ac commodates possible tilting movements ofthe chock 3 during roll deflection.

As is clear in the drawing, the bottom 51) of the pot is very thick soas to have as high resistance to bending as possible. Likewise, in orderto minimize any deflection in this strong and rigid bottom 5b, a centralrecess or cavity 7 is formed in the upper surface of the bottom 5b. Thisrecess or cavity is circular in plan so that the pressure transferringsurface or contact area between the flat bottom of the intermediatepiece or block 6 and the upper face of bottom 5!) of the breaker pot 5is reduced to a wide circular ring or annular contact surface or area5e.

The wall of the breaker pot 5 provides the breaking point cross-sectionand to assure this an internal annular groove 5d is formed in this Wallto provide the breaking point cross-section at 50. Due to the fact thatthe pressure forces exerted at the areas or surfaces indicated by thearrows overlap, that is, the top of the supporting ring 4 bears againstor attacks the undersurface of the flange or rim 5a While the adjustingscrew 1 via the block 6 exerts pressure on the annular contact surface5e of the bottom 5b of the breaker pot, only tension stresses arecreated in the wall of the pot particularly at the breaking pointcrosssection 50. Thus, as shown, the respective pressure contact areasare both annular or of ring shape With their points of application lyingin vertically displaced planes and one contact area being radiallyoutward to the other. This relationship provides the overlapping of thepressure forces so that tension stresses are created in the wall of thebreaking pot. In other words, the breaker block of this invention,contrary to known prior art arrangements, does not establish any bendingor shearing stresses in the breaker block.

This tension stress is ensured by the fact that the opposing forces areexerted over areas of contact that are radially spaced from one anotherby a distance equivalent to the thickness of the wall of the pot andwhich areas of contact are in planes displaced axially of the line ofapplication of the forces so that the pressure forces are trulyintroduced into the breaker block in an overlapping manner.

If the system is overloaded, the bottom 51) with part of the wall of thebreaker pot 5 breaks at the breaking point cross-section 5c. The nowseparated upper and lower parts of the breaker pot can be easilyremoved, after the parts of the bipartite or split supporting ring 4 aretaken away laterally. In order to put in laterally below the screw-down1 a new one-piece breaker pot 5, together with-the inserted intermediatepiece or block 6, the adjusting screw 1 need not be moved up. Apre-condition is, that the intermediate piece 6 or the space between thebottom and the chock 3 is high enough. Thereupon, the parts of thesupporting ring 4 are inserted again between the rim 5a of the breakerpot and the chock'3. To secure the position of the supporting ring 4, acentering recess 3a is provided in the upper surface of the chock 3;

It will be obvious to those skilled in the art that various changes maybe made in the invention without departing from the spirit and scopethereof and therefore the invention is not limited by that which isshown in the drawing and described in the specification, but only asindicated in the appendedclaims.

What is claimed is:

1. In an overload protection arrangement for interposition betweenmachine elements subjected to opposing pressure forces, a breaker blockincluding a body member having spaced pressure receiving faces and aportion extending therebetween, said faces being disposed in parallelplanes spaced axially of the line of application of force, and one facebeing spaced radially of the other whereby when said faces are subjectedto opposing pressure forces the portion of the breaker block betweensaid faces is subjected to tension stress.

2. An overload protection arrangement for interposition between machineelements subjected to opposing pressure forces comprising a body memberincluding abend resistant bottom, a wall structure and a flangeextending outwardly from said wall structure in spaced relationship tothe bottom, said bottom having a thickness in excess of the thickness ofthe flange, a load receiving member within the body and bearing againstthe inner surface of said bottom and a load transmitting member bearingagainst the undersurface of said flange, whereby when said body issubjected to opposing loads tension stresses are created in said wallstructure.

3. An overload protection arrangement as claimed in claim 2 and in whichsaid bottom is provided with a cen- 4 tral recess to delimit incombination with the inner surface of said wall structure an annularpressure receiving face.

4. An overload protection arrangement as claimed in claim 2 and saidwall structure having an internal groove at a location between saidbottom and said flange to define a breaking point cross-section.

5. An overload protection arrangement as claimed in claim 2 in whichsaid load transmitting member is a splitring.

6. An overload protection arrangement as claimed in claim 2 in whichsaid load transmitting member has an extent parallel to the. line ofapplication of force in excess of the distance between the undersurfaceof said flange and the outer surface of said bottom and said loadtransmitting member surrounding said wall structure in closefittingguiding relationship to confine the material of said wall structure.

7. A breaker block construction for interposition between machine partssubjected to load, particularly between an adjusting screw and a rollchock in a rolling mill, said breaker block comprising a body memberincluding a bottom and atwall structure, a flange extending outwardly ofthe wall structure and having a surface parallel to and spaced from saidbottom, said bottom being thicker than said flange and said wallstructure, the inner surface of the bottom and the undersurface of saidflange defining pressure receiving contact areas respectively spacedaxially of the lines of transmission of pressure forces with one areabeing radially spaced from the other by the thickness of said wallstructure so that upon application of forces opposing to said areas saidwall structure is subjected to tension.

McIlvried Oct. 25, 1932 Bailey Oct. 7, 1952

1. IN AN OVERLOAD PROTECTION ARRANGEMENT FOR INTERPOSITION BETWEENMACHINE ELEMENTS SUBJECTED TO OPPOSING PRESSURE FORCES, A BREAKER BLOCKINCLUDING A BODY MEMBER HAVING SPACED PRESSURE RECEIVING FACES AND APORTION EXTENDING THEREBETWEEN, SAID FACES BEING DISPOSED IN PARALLELPLANES SPACED AXIALLY OF THE LINE OF APPLICATION OF FORCE, AND ONE FACEBEING SPACED RADIALLY OF THE OTHER WHEREBY WHEN SAID FACES ARE SUBJECTEDTO OPPOSING PRESSURE FORCES